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Subject: Re: [rfc 3/3] perf, x86: P4 PMU -- export ABI part of event config
 to userspace
From: Peter Zijlstra <peterz@infradead.org>
To: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Ingo Molnar <mingo@elte.hu>, LKML <linux-kernel@vger.kernel.org>,
        ming.m.lin@intel.com, eranian@google.com
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Date: Wed, 24 Nov 2010 10:02:36 +0100
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On Wed, 2010-11-24 at 11:48 +0300, Cyrill Gorcunov wrote:
> On 11/24/10, Peter Zijlstra <peterz@infradead.org> wrote:
> > On Wed, 2010-11-24 at 01:46 +0300, Cyrill Gorcunov wrote:
> >> plain text document attachment (x86-perf-export-abi)
> >> Due to tight 64 bit size of event config field (where we have to track
> >> pretty lot of info during event lifetime) some bits are to be exported
> >> via header into userspace.
> >>
> >> Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
> >> CC: Lin Ming <ming.m.lin@intel.com>
> >> CC: Stephane Eranian <eranian@google.com>
> >> CC: Peter Zijlstra <peterz@infradead.org>
> >> ---
> >>
> >> Note that I don't like much the idea to export anything into userspace
> >> but it seems there is no other choise. So there is a minimum which should
> >> be exported.
> >
> >
> > Could you say what exactly is exposed to userspace and why?
> 
> yes, we need two enums to be exported, because we use custom encoding,
> which is described in first patch. peter i'll describe more detailed
> in a couple of hours, ok?

Sure, but have you seen my sysfs patches? wouldn't describing the format
in there suffice?

http://lkml.org/lkml/2010/11/17/154